1. Field of the Invention
The invention relates generally to the field of drilling multiple lateral wellbores to produce fluids from a subsurface rock formation. More particularly, the invention relates to techniques for drilling and fracturing multiple lateral wellbores to increase fluid recovery from the rock formation.
2. Background Art
Certain types of subsurface rock formations are hydraulically connected to the Earth's surface for production therefrom of oil and/or gas. In such formations, a drainage network of lateral wellbores is drilled generally along the bedding planes of the formations. The relatively large drainage area created by such wellbore networks may enable rock formations having relatively low permeability to produce commercially valuable quantities of oil and/or gas.
An example drainage network is shown in FIG. 1. To minimize damage to the surface, a number of wellbores may be drilled from relatively small area surface locations prepared for operation of a drilling unit (not show). Such locations are shown schematically at 12 and 14 and are typically referred to as “pads.” A plurality of laterally extending wellbores 10 is drilled, initially vertically, and then along selected trajectories laterally along a selected (“target”) formation, shown generally at 15. Typically the lateral wellbores 10 will be laterally spaced apart from each other in a selected geometric arrangement within the target formation 15. A typical arrangement of lateral wellbores is shown in FIG. 1 in which the lateral wellbores 10 drilled from a first pad 12 extend generally in parallel toward the end of lateral wellbores 10 drilled from an adjacent second pad 14. However, the lateral displacement of the lateral wellbores 10 is typically limited so that wellbores from adjacent pads generally do not extend past each other (i.e., traverse the same area of the target formation 15) as shown in FIG. 1.
There continues to be a need to improve fluid recovery from subsurface rock formations using networks of lateral wellbores.